BUYER BEWARE

The automotive aftermarket is a vast shopping mall of major and minor parts for the casual hobbyist, the professional engine builder and the dedicated racer. Deciphering the information (and misinformation) can be a daunting task for even the most astute customer who wishes to buy quality parts at fair prices. Comparing ads or catalogs is now a national pass-time and sales are often won or lost for a few CFM, a few more degrees of duration or several horsepower.

We at World Products / Bill Mitchell would like to offer thoughtful readers some insights which might be helpful to evaluate deals and see “between the lines” among competitors claims.

There are several topics which can either inadvertently or intentionally cause a consumer to become confused or misled. We’ll present a few for you to consider.

How many ads have you seen with the phrase “CNC machined” blaring across the page or screen? These initials represent “computer numeric control”, a process by which locations on a part are assigned digital values which are then programmed into a complex three, four or five axis cutting machine. This program then directs the angles and cuts or drills to be performed on the part and any number of the same design which come after. The implication is that parts so machined have superior quality and in fact superior design. Well, not necessarily so.

CNC is simply an accepted, automated way to cut metal-in a perfectly repeatable way-from part to part. This process is remarkably efficient, rapid and precise. That is its major value. The point to understand is that if the prototype of the part is a poor design, you’re just going to replicate a poor design with CNC.

In the case of cylinder heads, the perception being offered in some advertising is that CNC is superior to hand porting (generally, only from the time and repeatability factors) or “as-cast” heads. Heads with cast chambers and ports can be superior to machined parts if the part used as the pattern for CNC digitizing is an inferior design. The pattern maker for the tooling determines the accuracy and repeatability of a cast part. In short-do your homework. Compare data such as flow at lift under the curve, not just total lift at a number your cam can’t attain. Don’t just buy a part because it’s CNC machined, check its credentials. There may be an equal performing as-cast head that’s less expensive or a better value.

“You can’t run a Dominator carb on a street-driven car.”  “The formula says you only need (fill in your most frequently quoted number) CFM carb for that size engine.” OK, let’s return to the dark ages.

The truth is, recent cam designs, intake and cylinder head science can move much more air through engines than previously thought possible on pump gas engines. This has also led to a trend of less spark lead and the wider usage of roller cams, both hydraulic and solid, on street-capable engines. The further really significant trend of late is the move to larger displacement engines, either through stroker cranks or custom blocks which permit the use of larger strokers. All these factors can really use the flow of 4500 Series carburetors.

The modern 4500 has been steadily refined also, incorporating power valves and street friendly linkage. It’s no longer the “on / off switch” once demanded in drag race-only applications. It’s our finding that you can make more streetable power this way if your total combination is planned for it. In fact, that’s how we build most of our engines.

Ever read the fine print in engine package ads? With some engine builders’ promotions, it pays to have an eagle eye and some common sense. Most such ads will announce a given engine displacement, a max HP rating and a cost. Fair enough-but somewhere near the heading for a group of such engines it may say “Minus carb and ignition”.

Well OK-we can assume that the builder did dyno such a combination and achieve the advertised power with a dyno-optimized carb and distributor. But he’s not giving you those parts. The carb and or distributor you buy when you get the engine home may produce significantly less power than the builders’ parts because he’s had a dyno to optimize them-you don’t. You may be a pretty sharp tuner but you can no longer be sure that your new bullet makes the 922 ¼ HP the builder advertised. So why order it that way?

Of course you can order the engine with duplicates of those parts from the builder but now you’re paying a materially higher price than the advertised one. Carbs can add $500-$1500 and a quality distributor $200-$600 to your expenditure.

Let’s look at the “offshore parts” debate. “I don’t want any of that Bling-Blang (substitute foreign country of your choice) crap in MY engine!” The fact of the matter is that many countries are producing a lot of the high performance parts in use here today. It’s truly a global manufacturing community. Argentina, Australia, Canada, China, India, Japan and the UK, to name a few, all manufacture and export parts of much higher quality than they did even five years ago.

Many speed parts are cast or forged under contract offshore in rough form and machined by the parent company here in the US. Lower costs to produce these parts offshore allow some of the biggest names in the speed industry to offer a discounted product line to the US consumer. This has allowed for example, the proliferation of stroker cranks to become so popular at reasonable cost. The key here is that you can buy some pretty hefty street / strip power these days for a very reasonable amount of money. Look for value, not just a “Made in USA” label. Oh-and just because your next crate engine builder can boast “Made in the USA”, chances are parts like the crank, rods, balancer, valves, springs, fasteners or breathers were not.